The present disclosure relates to fluid actuated grippers of the type employed in automated workpiece handling devices which clampingly grip and transfer a workpiece from one station to another. More particularly, the present invention relates to adjustable article sensor assemblies for such fluid actuated grippers which can detect specific orientations of the jaw member portion of the fluid actuated grippers.
Fluid pressure actuated grippers are widely employed and typically take the form of a pneumatic or hydraulic differential motor whose cylinder is fixedly mounted to a transfer device. At the forward or rod end of the cylinder housing, a gripper jaw mounting structure is fixedly mounted on the cylinder to pivotally support a pair of opposed gripper jaws which are coupled to the piston rod of the motor by a linkage. This arrangement allows movement of the piston in one direction so that the jaws are pivoted to an open position, and upon movement of the piston in the opposite direction the jaws are driven to a closed workpiece gripping position.
In typical operation, the gripper jaws close upon a workpiece near the edge of same, and the gripper advances to position the gripped workpiece in operative relationship with a work station or portion of a production line. The gripper then opens to release the workpiece and retracts from the work station or production line while the work operation or task is performed. At the conclusion of the operation or task, the gripper advances back into the work station and the jaws again close upon the workpiece and carry it away from the work station.
Such fluid pressure actuated grippers are generally designed for use with particular workpieces to be transferred and with specific work stations or production lines. For example, some workpieces and/or work stations may require wider or narrower gripper jaws, different types of gripper jaws, gripper jaws that open at different angles, jaws that require different clearance requirements, etc., to complete a particular task. Furthermore, such grippers carry workpieces which may be of a variety of sizes or thicknesses.
A known problem associated with production lines employing numerous grippers, which are each completing a specific task as part of a sophisticated series of operations, is that if one gripper fails to complete its task, it could create multiple failures along the production line. This failure has the potential of stopping the entire production line, thus, delaying completion of the operation, as well as the possibility of delaying other operations that rely on the completion of this operation. A common type of failure is the gripper failing to grip the workpiece, the workpiece falling out of the gripper while it is being carried, or the workpiece carrying more than one workpiece at a time (double sheeting). Consequently, these failures translate into increased costs and potential losses in both time and revenue.
Accordingly, it has been contemplated, in an attempt to mitigate such failures, to include sensors on each gripper so that it can detect the presence of the workpiece, lack thereof, or even control the amount the jaw members of the gripper can open or close for particular gripping applications. Such sensors provide interactivity between the gripper and the workpiece itself, allowing the production line to be more intelligent. In fact, as particular tasks are being conducted or completed on the production line, it can be configured to require proper sensor readings at each step of the line, and more specifically, require proper sensor readings before each subsequent step in the line is initiated. This assists in eliminating the entire production line failing and/or being damaged when an initial failure is not immediately detected. In addition, such sensors help monitor the reliability of the line, as well as localize any problems with same.
Sensors for grippers for the purposes described above are known. Examples of such sensors are those used in jaw tips or on the jaw members to detect the existence of a workpiece when being manipulated by the gripper. Another common example is the sensor assembly used for pneumatically powered enclosed clamps. Such a clamp uses a piston rod that includes a targeting device attached thereon. A sensor module is attached to the periphery of the clamp such that a sensor in that module can detect the targeting device at a certain point along the stroke of the jaw arms. The sensor mounts to the sensor module via a locating hole through which the sensor is disposed in order for it to contact the targeting device. The sensor module includes a plurality of locating holes incrementally spaced, and each one configured to accept the sensor. The sensor may be adjusted by separating it from one locating hole in the housing, and moving the sensor to a new position using an alternate locating hole. Typically, these locating holes in the housing have been marked to identify sensor mounting locations that correspond to specific orientations of the clamp (i.e., jaw arm rotation). In other words, these locations establish the sensor mounting location in which the sensor will signal when the clamp is in a specific jaw arm rotation.
Accordingly, an illustrative embodiment of the present disclosure provides a fluid actuated parts gripper assembly. The fluid actuated parts gripper assembly comprises a pair of opposable pivoting jaw members, a fluid driven actuator, first and second linkage structures, a sensor target, a mounting and a sensor. The first linkage structure is driven by the fluid driven actuator. The second linkage structure is coupled to the linkage structure and at least one of the pair of opposable jaw members. The fluid driven actuator causes the first linkage structure to move, which causes the second linkage structure to move at least one of the pair of opposable jaw members. The sensor target is coupled to the second linkage structure and is movable therewith. The mounting is located adjacent the sensor target, and the sensor is mounted on the mounting allowing the sensor to detect the sensor target.
Further embodiments of the illustrative gripper assembly may include the mounting being adjustable relative to the sensor target, the sensor fixed relative to the mounting, and the mounting configured to receive the target. Additionally, the embodiment may have the sensor target being moveable within the mounting, the mounting further including a slot within which the sensor target is moveable. The mounting may further comprise at least one slot configured to receive a fastener that selectively fixes the mounting to the gripper. The adjustment member may also be coupled to the mounting for incrementally adjusting the location of the mounting relative to at least one of the pair of jaw members.
Another illustrative embodiment of the present disclosure provides a fluid actuated parts gripper assembly having an adjustable sensing mechanism. The fluid actuated parts gripper assembly comprises a body, a pair of opposable jaw members, a cam pin, a linkage structure, a sensor target, a mounting, and a sensor. The body includes a yoke structure that is defined at one end by a pair of spaced apart wall members, and a fluid driven actuator at an opposite end. One of the pair of spaced apart wall members includes an opening disposed therein. At least one of the pair of opposable jaw members is pivotable, and each of the pair of opposable jaw members includes through-slots located therein. The cam pin extends into the through-slots of each of the pair of opposable jaw members and is disposed through the opening in one of the pair of spaced apart wall members. Additionally, the cam pin is movable within the opening. The linkage structure is driven by the fluid driven actuator and is coupled to the cam pin. The sensor target is coupled to the cam pin and is movable therewith. The mounting is configured to receive the sensor target, and the sensor is mounted on the mounting.
Another illustrative embodiment of the present disclosure provides an adjustable spacer for a sensor mounting on a fluid activated parts gripper. The adjustable spacer comprises a member having a plurality of sides. Each of the plurality of sides is located at a different length from a location on the member. The illustrative embodiment may further include the location being a bore disposed through the member. The member itself may have opposed surfaces with each being non-equidistant from the location. The member may also be hexagonal with opposed surfaces each being non-equidistant from the location.
Another illustrative embodiment of the present disclosure provides a fluid actuated parts gripper assembly of the type having a gripper body with an opening disposed therethrough configured to receive a pin that is movable in concert with at least one of a pair of opposable jaw members. In addition, the fluid actuated parts gripper also has an adjustable sensor mounting assembly disposed thereon. The sensor mounting assembly comprises a mounting body, an adjustable spacer member and a fastener. The mounting body is attachable to the gripper body over the opening. In addition, the mounting body includes an aperture disposed therethrough and a stop member extending from a portion of the aperture. The adjustable spacer member includes a plurality of sides with each located at a different length from a location on the member. The fastener is disposed through the aperture of the mounting body to selectively secure the adjustable spacer member and the mounting body to the gripper body such that one of the plurality of sides is adjacent the stop member. The illustrative embodiment may also comprise each one of the plurality of sides of the adjustable spacer member to locate the mounting body to a unique position relative to the gripper body.
Another illustrative embodiment of the present disclosure provides an adjustable spacer for a sensor mounting on a fluid activated parts gripper. The adjustable spacer comprises a member having a periphery disposed thereabout. The periphery is segmented into a plurality of discrete surfaces such that each of the plurality of discrete surfaces is located at a unique distance from one location on the member.
Additional features and advantages of the gripper assembly will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrated embodiment exemplifying the best mode of carrying out the gripper assembly as presently perceived.